Magnetic wedge for dynamo-electric machines.



slots' are made deeper BENJAMIN F. LEE, OF SCHQOLFELD, VIRGINIA.

MAGNETEG WEDGE FOR Specification of 'Letters latent.

DYNAMIC-ELECTRIC MACHINES.

Patented Deo. 30,1913.

Application filed December 14, 1912. Serial No. '236,748.

Y To all whom it may concern is inagnetized by coils of wire seated in a I plurality of grooves or slots formed in its edge, the object of the invention being to produce in a machine or" this type a coil carrying member upon which the` wire may be sily and quickly wound by threading .it through the slots or grooves which are inade deeper than the coils require to perinit ready winding. After winding, the coils are crowded toward Athe outer ends of the grooves or slots by magnetic wedges driven linto the bottom of the slots against the coils.

In certain types of induction motors, the

stator or rotor is commonly made with a number of open radial grooves or slots, the open ends ot which are ot less width than the remainder of the slots, and are known inthe art as overhang or partially closed slots. Within these slots are placed the exciting coils. Amongthe advantages to be derived troni such a construction may be mentioned low magnetizing current; low core loss; and a high power fact-or. The most serious objection to these overhang slots arises from the ditheulty of'winding the coils therein especially when repairs, such as replacing one or more damaged coils, are" to be made. This objection is wholly overcome by the present invention, as the than required tor the coils, thus giving plentyot room 'tor threading the wire through the slots without endangering its insulation. After replacing the'coil, the spaces in the slots are filled by driving'a novel magnetic wedge in the lower end ot each slot against the lower coil.

De tective coils may substituting torni wound coils` therefor, or hy threznling the wire through the slots. ln the latter case, the increased length oi slot gives full and sutticient room for that part of the coil which has to he threaded into a slot below another noil. Aor in the bottoni ot the slot, and particularly when the coil is nearly wound, the slot, in the be replaced, either by present type of machine, becomes crowdedl and the insulation on the wire is liable to be damaged. No such trouble will, be en countered in windingcoils on machines oo nstructed under the present invention, owing to the increased depth of the slot which pro vides all the space necessary Jfor the passage of the wire.

In the drawings forming a part of this specification, Fio'ure i is an end elevation of a portion otP a stator of an induction dynamo-electric machine constructed in ac* cordance with the present invention. Fig. 2 is a sectional view on the line 2-2. Fig. 3 is a side view ot the improved magnetic wedge partly in section.` Fig. l is an end view of the same. Fig. .5 is a cross-sectional view of the magnetic wedge. Fig. 6 is an end view of a rotor with the invention applied. i

ln the drawing, l0 indicates the stator ot an electric generator or motor, made usually of laminated iron in annular form with a plurality of slots or grooves l1 in its concave surface to reeeiv'e windings or coils of insulated wire l2. The grooves' or slots l1. open on the concave surface of the stator 10, but are closed at tlieirppposite ends. The 'teeth .i3 between the slots l1 are provided at their tree ends with thin, laterally projecting lugs or ribs 14; which overlie the open ends of the slots and partly close them., Jforming what is known as overhung or partly closed slots. lVithin each slot 1l and bearing against the overhanging lugs or ribs 14 is a plate or strip 15,' preferably made of some non-magnetic material, against which that part ot fa coil 12 in the open end ot the slot abuts. The slots 'll made deeper than required to contain the two coils `which are placed therein. to a'llford sutlicient room :for threading the coils there through when 'winding without crouf'ding oi; undue friction which endangers the insulation of the wire, particularly when threading the wire for the undermost coil in i the bottom ot the slot, as shown at A, Fig. l. the coils have been wound, they are fon d to the outer ends of the tained 'there h v means ot a wedge 1G driven into each' slot hetween its bottom wall and the lowerniost coil as shown in the drawing. This wedge lil is a laminated i structure, made not a nnmhcr ot thin iron plaies l? cut or I punched in the proper shape to tit the spa/ce l in 'the slot below the coil and connected by a vedges of the plates 19 are'tapered or rounded as shown to facilitate -the introduction and driving of the wedge in to the slot, The

' ends ot the wedges may project. slight-ly beyond the slots on each side if desired. Among .the advantages of this construction is the .placing of the coils nearer the air gap sothat the lines of torce will cut the coils instead of passing above theml` as in those constructions which place the wedges between the outer coils and the lugs or ribs 14. There being only a thin non-'magnetic plate or strip .l5 between the coils and the pole faces ofthe teeth 13, there are practically no electrical losses due to eddy currents, nor` magnetic leakage. Another advantage of the hereindcscribed construction resides in the ease and rapidity with which machines may be repaired lby threading the wire to form a new coil through `the slots instead of substitutinga` form wound coil for the defective one. lVliere form wound coils are used that portion of the coil in the bottom ofthe l slot can not be removed therefrom until the other coil in the outer part ot the'slot has been raised and wholly withdrawn therefrom, which in the case of small machines presents two ditiiculties. In the first ot these the ends till the field bore thereby making it diieult for the workmen to remove the damaged coil and putin a new one, and, seeondly, in raising the ends ot' coils, it is necessary to pull them up a considerable distance thereby bending the end turns which is liableto damage the insulation of the wire especially if the machine has been run tor sometime, in which case, the insulation has become dry and is easily damaged. No such ditliculties are encountered when the new coils are applied by threading the wire through the slots. But inl threading the l i l l l l l l coils in machines as at present constructed there is great danger ot wearing the insulation from the wire as it is passed through the lower portion of the slot owing to the crowded condition of the slot as it tills with wire. It is this ditliculty which the present invention seeks to overcome by making the slot deeper than necessary to hold the coils, and after winding the coils to illthe extra space below the undercoil with a magnetic wedge. Another advantageous point in this construction .is that the coils after being threaded in the slot and betere insertion of the wedge, may be -pulled out at one side and wrapped with terial, after which they may be drawn back into position, the extra vdepth olI the slots at-A fording plenty ot space for this purpose.

Fig. (5 illustrates a rotor 20 provided with radial grooves or slots 1l ot greater depth than. required for the coils with the coils l2 held in place by magnetic wedges 1G in the bottom of the slots, the constriwtimi and arrangement being the same as that used in the stator l0.

that l claim is,-

ln a dynamo electric machine. the combi nation with a. magnetizable member having a plurality of coil containing slots ot greater depth than required to hold the coils, coils seated within said slots, and means at the outer ends ol said slots to prevent the escape ol lsaid coils, of4 a laminated magnetic wedge in each Slot having straightparallel opposite sides and a convex semi-circula connecting side to fit closely said slot, and a .shallow concave side opposite the convex side to hear against the coil and hold it securely in the slot.

ln testimony whereof I ha vc hereunto set my hand in presence of two subscribing witnesses.

BENJAMlN F. LEE. Witnesses J. A. GUY, O. T. Jnrrnins. 

